Described are compositions containing quinones that show activity in enhance DNA repair and/or prevent damage to DNA. The quinones are thymoquinone, lapachol, myrtucommulone C, or mixtures thereof, and can be formulated into cosmetic compositions for topical administration to a subject in need thereof. The cosmetic compositions can also include sunscreens, surfactants, sunless tanning agents, desquamation agents, antiperspirants, colorants, preservatives and mixtures; and a cosmetically acceptable carrier. The compositions should find use in methods for treating the signs of ageing in mammals via topical application to the skin or hair of the mammals.